...How can there be a shadow ban on support tickets?! Even if there was such a thing as shadow banning on itch.io (that would be news to me).

From what our admins explained recently, support currently handles hundreds of tickets a day. That's the more likely cause.

i will like to heard the community experience with this issue. 

I once got a reply after reporting a bug. For other things, there were no responses. 

Most of the time there is no need for a response. Especially for the things you see in community threads. People do not want answers, they want their case to be worked on.

And there might be something fundamentally wrong in how tickets/support requests are queued. It seems as if requests can get lost. Ignored. Misunderstood. There was a virus I told them about. They did absolutely nothing for several months. And I believe to remove an indexed malware to be more important than all those threads about people wanting their game to get indexed faster. The virus was since removed, but probably because I wrote them again, and not because of my initial ticket. This is very worrying. With over a million projects, such requests should not get lost. Because then you get things like I already encountered: malware with an age of up to two years. Out in the open. Uncontested. If I remember correctly, there were even comments on the page about it being a virus. 

I fear that people are not motivated to report malware, because they do not see results. Not even after waiting several weeks. I certainly lose motivation over that. Why bother reporting viruses, if Itch does absolutly nothing from my perspective.

As answered by our moderator in this thread, and our administrator in one of the threads you linked, we process hundreds of tickets per day. We are constantly working to improve our flow and avoid missing issues, but we are a small team doing our best.

(I think it is also worth highlighting that the examples you provide above are years old, and do not reflect the increase in support staff nor any other process we have implemented to improve our support desk flow. Additionally, the support ticket you filed with us is less than 12 hours old, it seems that you opened this topic within minutes of filing your ticket, and thus you did not really give us a fair opportunity to get back to your ticket in the first place.)

As highlighted by hechelion earlier as well, I have also personally begun tracking and pushing up support issues that are posted in the forum in order to optimize this process further, but I also have a multiude of roles at itch.io, and as an average human being, I only have so many man-hours in the day, as do the rest of our staff that works on processing support tickets. We naturally have to prioritize cases the higher priority they are, and certain matters require far more attention than others (for example, search indexing, while important, is much lower on our priority list compared to managing account issues, payment issues, addressing game reports, or anything that requires our immediate intervention; search indexing is only one part of the site, and we highly recommend that your promotional efforts be focused towards off-site promotion, rather than relying on being indexed into the new releases section, which is commonly highly populated and has new content being added to it basically every few minutes). 

Thanks for your patience!